1. Field of the Invention
The present invention relates to cables in general and, more particularly, to electrical transmission cables.
2. Description of the Prior Art
Heretofore, commercial logging cables consisted of a plurality of conductors wrapped with armor where the armor may be used as the return path for signal conductor. However, such cables cannot be used for very high frequency signals since the armor offers a high skin effect resistance as a return path. Alternatively, an armored cable such as that described in U.S. application Ser. No. 192,883, filed Oct. 27, 1971, now U.S. Pat. No. 3,916,685, assigned to Texaco Inc., assignee of the present invention, is cable of very high frequency signal transmission but may not be readily adaptable to commercial logging tools designed for multiconductor cables.
The present invention provides an armored multiconductor coaxial cable for both high frequency signal and low frequency signal transmission in which a plurality of conductors, comprising groups of conductors, form a shield for an inner conductor and are capacitively coupled so that each conductor group may carry a difference low frequency signal or a direct current voltage. The cable of the present invention is readily adaptable to commercial logging tools designed for multi-conductor cables.